Tetrahedral packages have been manufactured and distributed for many years, and Tetra Pak® has been developing such systems since 1950. However, normal tetrahedral packages have a drawback, since they are difficult to pack in a space-convenient way. Specific odd-shaped secondary boxes for packing such tetrahedral packages have been developed for handling transport and shipping. Such odd-shaped boxes are not only costly but also complicate the packing process in automatic lines.
The general shape of an irregular tetrahedron, and its mirrored version, that can be used to completely fill a cube has been known since at least the year 1900. In U.S. Pat. No. 3,347,363 an irregular tetrahedral package was disclosed which enabled tight packing within a cube. The general idea is that a cube can be filled completely by using a combination of irregular tetrahedrons and tetrahedrons with a mirrored shape thereof. An internet search of space-filling tetrahedrons reveals different possible packing patterns. However, the irregular tetrahedrons are not easy to assemble into a cube since neither the intermediate nor the final assembly is stable in itself. There is hence a need for additional support.
Swedish patent application no. 1350503-7 discloses a method for assembling a group of irregular tetrahedral packages having a first orientation and a mirrored second orientation. The method comprises the steps of providing an L-shaped blank having a rectangular central wall, a rectangular right wall and a rectangular left wall, arranging one tetrahedral package with a first orientation and one tetrahedral with a second orientation on each of the right wall, left wall and central wall, such that the cardboard blank can be folded into a cube by angling the right wall from an unfolded position and by angling the left wall from an unfolded position until the tetrahedral packages rest on top of the tetrahedral packages on the central wall. Thus, a cube has been produced of six tetrahedral packages. In preferred embodiments an adhesive is applied to the tetrahedral packages on the sides that abut sides of other tetrahedral packages in order to further increase the stability during packing. The method disclosed in the Swedish patent application no. 1350503-7 has, despite the fact that the irregular tetrahedrons are not stable during the intermediate or the final assembly thereof, found a way to overcome the problem by introducing the L-shaped blank.
However, there is still room for improvements when it comes to packing irregular tetrahedral packages into a cube shape. More specifically there is a need to for a system for filling and packing tetrahedral packages without the use of any intermediate blanks, adhesives or the like for creating stability during the packing process.